Warren Buffett boosting his stake in Apple Inc. has pundits predicting it is poised to hit $1 trillion in market value. But the iPhone maker isn’t the first to tread that lofty path.

PetroChina Co. crossed the milestone back in November 2007, when its mainland shares almost tripled in value in their Shanghai trading debut.

But the state-controlled energy company dropped below that level within a day and had fallen below $500 billion by March 2008. It now ranks fifth among Chinese companies, at less than half the market values of e-retailing behemoth Alibaba Group Holding Ltd. and e-payment giant Tencent Holdings Ltd. — which both traded above the equivalent of $500 billion at several points this year.

Apple topped $500 billion for the first time in February 2012. Currently, Amazon.com Inc., Microsoft Corp., Google’s parent Alphabet Inc. and Facebook Inc. are all half-trillion-dollar-plus companies.